1. Field of the Invention
This invention relates generally electronic equipment, such as computers, and, more particularly, to apparatus for coupling electrical assemblies to circuit boards.
2. Background Information
Electronic systems such as computers are typically constructed in a modular fashion from circuit boards, each circuit board generally performing a specific function. Each circuit board requires multiple electrical connections, which are generally provided by two part multi-contact electrical connectors. One part of the connector is mounted to the circuit board, while a mating part of the connector may be attached to another component of the system such as a rack, a chassis, a cable, or another circuit board (e.g., backplane circuit board). Successful mating of connector parts is needed for reliable electrical connections in the system.
A number of mechanisms are known for injecting a circuit board into a chassis or extracting a circuit board from a chassis. Such mechanisms may include lever arms pivotally coupled to the circuit board and arranged to engage projections formed on the chassis. Guide formations may be provided on the chassis to receive the circuit board and to guide the circuit board into position such that electrical connector parts mate with one another. The lever arms may be arranged on the circuit board so that when the lever arms are actuated, the circuit board is provided with a biasing force that serves to move the circuit board toward the rear of the chassis, thereby mating the parts of the electrical connector.
For circuit boards with connectors having a relatively large number of pins, large insertion forces may be required to mate the connector parts. For example, a large board may contain several multi-contact connectors, each connector containing several hundred individual contacts. Each contact requires the application of an insertion force to seat the contact. Thus, the total insertion force required to seat a large board may be 65 pounds or more. Moreover, individual contacts are easily damaged if the mating connector parts are not properly aligned when they come into contact with each other. This problem is especially acute where large forces are required to mate the connector parts.
Electrical connections may be made among various circuit boards in a chassis or between circuit boards in a chassis and components external to the chassis. Such connections may be provided through a backplane circuit board to which the other circuit boards are mutually installed. In some cases, a backplane circuit board does not provide all of the connections needed for a system. In addition, a backplane circuit board may not provide optimal (e.g., minimum length) routing of conductors in a system. Electrical connections can be made using cables between the boards or other components. Installation of cables for a large system, however, may be difficult and laborious. Furthermore, in some cases the use of cables in lieu of circuit boards may result in slower connections between components. In addition, connectors may be susceptible to damage during installation of such cables due to misalignment of connectors.
Circuit boards may encounter a variety of external loads. Some loads relate to environmental conditions while in service, such as shock or vibration. Other loads are encountered during assembly, such as those applied during installation or removal of components on the circuit board or other elements in a system. In either case, the loads may cause separation of or damage to individual contacts, reducing reliability of the system.
It would be beneficial to have an improved mechanism for inserting and ejecting electrical assemblies to and from circuit boards. It would further be beneficial to have an improved electrical assembly that promotes a reliable connection between circuit boards when a system encounters external loads.